Semiconductor devices are used in a variety of electronic applications, such as personal computers, cell phones, digital cameras, and other electronic equipment, as examples. Semiconductor devices are typically fabricated by sequentially depositing insulating or dielectric layers, conductive layers, and semiconductive layers of material over a semiconductor substrate, and patterning the various material layers using lithography to form circuit components and elements thereon.
In a lithography process, a layer of photosensitive material such as a photoresist is deposited over a material layer of a semiconductor device. The photosensitive material is patterned by exposure to light or energy passed through or reflected from a lithography mask having a desired pattern thereon. The photosensitive material is developed, and exposed (or unexposed, depending on whether the photosensitive material is positive or negative) portions of the photosensitive material are removed using an ash and/or etch process. The photosensitive material is then used as an etch mask during an etch process to pattern the material layer of the semiconductor device, and the photosensitive material is then removed.
A lithography mask is used hundreds or thousands of times to pattern semiconductor devices. Over time, lithography masks tend to become contaminated with debris, such as haze, that forms on the surfaces of the lithography masks. Thus, repair methods are occasionally required for used lithography masks, in order to remove the debris.
Corresponding numerals and symbols in the different figures generally refer to corresponding parts unless otherwise indicated. The figures are drawn to clearly illustrate the relevant aspects of the embodiments and are not necessarily drawn to scale.